Manometric characteristics of glossopalatal sphincter.

When a liquid bolus is held in the mouth, the posterior tongue and soft palate pinch together to prevent premature spillage of the bolus into the oropharynx. We propose that this glossopalatal closure acts as a glossopalatal sphincter (GPS). In this investigation, we studied glossopalatal closure by obtaining concurrent manometric and radiographic recordings of barium swallows in healthy volunteers. Manometry was done by both a continuous pull through method and also by a stationary catheter technique using a ribbon catheter with multiple sideholes spaced at 1-cm intervals. The results showed that when the mouth was loaded with a fluid bolus, the closed glossopalatal segment generated an asymmetric high-pressure zone with greater pressures toward the tongue and palate than laterally. With swallowing, the glossopalatal sphincter high-pressure zone relaxed and the glossopalatal sphincter opened to allow barium to flow from the mouth into the oropharynx. We conclude that the glossopalatal sphincter functions as a physiological sphincter in that it (1) generates a sustained high-pressure zone and closure when a liquid bolus is held in the mouth and (2) relaxes and opens with swallowing.